The addition of algicide to recirculated water, such as used in cooling towers and the like, to control algae growth and development is desirable, even necessary, because algae growing in such water impairs the utility of the water for cooling purposes and results in contamination and fouling of surface portions of equipment contacted therewith.
Although various chemicals and recirculated water treating procedures have been previously used, terbuthylazine (which is 2-(tert-butylamino)-4-chloro-6-(ethylamino)-s-triazine) has been found to be effective for controlling algae growth. Typically, a powdered or aqueous terbuthylazine-containing treating composition can be added to the cooling tower water on a batch (periodic) or continuous basis. Batch addition to recirculated cooling tower water may be undesirable because the treatment may be effective only for a brief initial period or because the terbuthylazine is not always present at desirable levels. For example, after batch addition, the amount of active agent present can decline for a variety of reasons, including deterioration, addition of replacement water to compensate for system water loss, and the like. With a decrease in the effective amount of active agent, an increase in algae growth in cooling tower water can occur, for example. On the other hand, the continuous addition of powdered or aqueous terbuthylazine to cooling tower water may be undesirable because of the costs of equipment (such as metering pumps and the like) and of maintenance.
Furthermore, the U.S. Environmental Protection Agency has taken the position that exposure of personnel to terbuthylazine, such as might occur with a prior art procedure of adding powdered or aqueous terbuthylazine formulations to cooling water, should be avoided because of potential adverse effects.
There is therefore a need for improved technology that enables one to treat the recirculated water of a cooling tower or the like with terbuthylazine in a relatively simple, cost effective, safe and efficient manner.